FPD-IG-175, FPD-UV-3000, FPD-VIS-300 User Manual
5
B.
A signal has been detected previously obtained, but is currently lost.
1.
Try steps listed under A.
2.
Inspect the active area of the
for any signs of damage.
3.
Try a higher input termination on the oscilloscope, but remember to return to 50Ω if this does not
work.
4.
Test the power supply:
a.
Units with internal batteries will typically operate for several years, but operation with CW
or high rep rate lasers can drain the batteries much faster.
If a load is present at the output,
current will be drawn from the batteries, so disconnect the
when not in use.
Remove top cover to replace the 3V lithium cells with Duracell Model DL2430, positive side
down.
b.
Units with an external power supply should at least receive the voltage that is printed on the
plug.
5.
You can terminate the detector in 1MΩ input of an oscilloscope to obtain a higher output
voltage signal but this will decrease the detector’s
by a factor of 5x10
5
.
C.
Increasing the power incident on the detector does not result in a higher voltage signal on
the oscilloscope:
1.
The detector is probably saturated. You should lower the power incident on the detector
to a level below the saturation point.
2.
Check that the photodiode bias voltage is correct. Check the power supply voltage is
correct and connected or check the battery voltage.
D.
The measured pulse shape is not as expected. The rise and fall times are too long or the
area around the peak is distorted and/or attenuated:
1.
Check that the photodiode bias voltage is correct. Check the power supply voltage is
correct and connected or check the battery voltage.